There's no business like show business, but there are several businesses like accounting.

Letterman’s line is a deadpan riff on the famous show-business boast “There’s no business like show business,” puncturing entertainment’s self-mythologizing with a mundane comparison. By adding “but there are several businesses like accounting,” he implies that the glamour and uniqueness claimed by performers is exaggerated, while many ordinary professions share similar structures: routine, rules, and repetitive tasks. The joke also plays on anticlimax—swapping a romanticized industry for one stereotyped as dull—to highlight how celebrity culture inflates its own importance. In a broader sense, it’s a comic reminder that work is work, and that the “specialness” of show business is often a matter of branding rather than substance.